Heat-exchange apparatus



May 20, 1930.

G. D. MANTLE HEAT EXCHANGE APPARATUS Filed April 9, 192e 2 Sheets-Sheetl May 20, 1930- G. D. MANTLE HEAT EXCHANGE APPARATUS' Y 2 SheetS-Sheec 2Filed April 9, 192e FIELE.

Patentedl May 20, 1930 UNITED STATES PATENT orFicE GREGORY D. MANTLE, OFPITTSBURGH, PENNSYLVANIA, ASSIGNOR, BY .MESNE ASSIGN- MENTS, TO SURFACECOMBUSTION COMPANY, F TOLEDO, OHIO, A CORPORATION OF NEW YORKHEAT-EXCHANGE APPARATUS Application led April 9,

This invention relates to heat exchange apparatus and more particularlyto the type adapted to be used in connection With a fiue chamber for thepurpose of utilizing the heat si ot' the combustion gases passingtherethrough for raising the temperature of a fluid such, for

example, as air` passed through the apparatus.

Although the most efiicient form of heat exchanger is the straightcounter flow type, in Which the direction of fioiv of the fluid passingthrough the apparatus to be heated is opposite to the direction of flowof the heating gases. this type has certain practical disadvantageswhich result from the fact that that part of the apparatus which isexposed to the highest temperature of the heating gases is also the partconveying the hottest fluid to be heated with the result that thetemperature of the material from Which the heat exchanger is constructedat that point may be so high as to materially reduce the effective lifeof the structure. In view of the fact that the counter fion' type ofheat exchanger insures the greatest mean temperature difference betweenthe Huid to be heated and the heating gases, this type of apparatustakes the greatest advantage of the convected heat but fails on theother hand to efiiciently utilize the radiant heat available fromsources outside of the heating gases such. for example, as the bricksettings of the. associated Hue chamber or the like. This is due to thefact that such heat is most intense at the. point Where the heatingfluid enters the apparat-iis which. in a counter How type. is also thepoint Where the Huid to he heated is hottest so that the heat transferat this point is relativelv low due to the fact that. as stated inStefan-Boltzmanns lau'. Athe rate of heat transfer bv radiation from ahotter to a. cooler body is proportional to the difference in the fourthpowers of their absolute temperatures.

An obiect of this invention is to provide a heat exchanger apparatus ofsuch construe.'- tion and arrangement as to utilize to the greatestadvantage not only the radiant and convected heat of the heating gasesbut also the radiant heat from sources outside the heating fiuid such,for example, as the brick 1926. Serial No. 100,862.

settings of the flue'chamber or similar associated structure.

A further object is to provide a heat eX- change apparatus of suchconstruction and arrangement as to obtain the utmost effect from theheat radiated by the associated structure and wherein the fluidsubjected to such heat is so controlled as to insure the most efiicientheat transfer and to maintain the teinperature of the material fromwhich the apparatus is constructed within safe limits.

These and other objects Which Will be apparent to those skilled in thisparticular art are attained by means of the invention illustrated in theaccompanying drawings, in which Figure 1 is a sectional viewillustrating the' construction of a single unit constructed inaccordance with one form of this invention. Fig. 2 is a horizontalsection on the line 2 2 of Fig. 1. Fig. 3 is a cross section on the line3-3 of Fig. 1. Fig. 4 is a view similar to Fig. 2, showing an apparatusformed by a single unit and Fig. 5 is a view similar to Fig, 1, showinga different modification of this invention.

In the particular embodiment of this invention illustrated in theaccompanying drawings, a. conduit or passage for a stream of iuid, suchas air to be heated, is so formed in each section as to cause the streamof air to flow in a direction counter to the direction of How of theheating gases passing through the apparatus. In the illustratedembodiment, this counter current owing stream of air will be hottest atthe bottom of the apparatus and the. heat exchange at this point Withthe counter current stream Will be relatively low. In order to take theutmost advantage of the radiantlieat of the associated brick Work or thelike. and to obtain the most efficient heat exchange underStefan-Boltznianns law a relatively cold stream of air is fed directlythrough the apparatus and across the bottom or hottest part thereof. Inthis Way the greatest mean temperature difference possible is maintainedbetween the heating gases and the surrounding brickivork or otherassociated structure on the one hand and the fluid to be heated on theother hand, at the same time, this portion of the apparatus is kept atOLS a temperature within the safe limits of the material forming theapparatus. In order to insure a sufficient ow of air through thel vent aflow through the counter' current passage except when the flow throughthe cross current passage is suflicient to maintain the temperature ofthe. material within safe limits and to insure the most eilicient heattransfer as a result of radiation. In other words, the flow of airthrough the cross current passage or conduit is-lnaintaincdsubstantially constant as long as the total flow is above apredetermined point, regardless of variations in the 4tota-l amount ofair flowing through the entire apparatus.

It will be apparent from an inspection of Figs. 3 and 4 that any sizeapparatus desired can be formed by using the necessary number ofsections, it merely being a matter of manifolding to providesufliciently large inlets and outlets to accommodate the number ofsections used.

Each section is associated with an inlet 6 leading from a supply line 7toa manifold 8 through which fluid passes into a conduit or passage 9which extends downwardly through each section in a circuitous routeformed by suitably positioned baflles 10. Adjacent the lower portion ofeach section the conduit or passage 9 is provided with an outletl 11through which the counter current flowing stream of air emerges into anoutlet duct or manifold 12 leading to an outletlB.

The supply line 7 also communicates with a second air inlet 14 leadingto a vertically extending manifold 15 which extends downwardly along theedge of the apparatus below the manifold 8 from which it is separated byan extension 16 ofthe upper baille 10. T he manifold conduit or passage15 is separated from each section by walls 17. The

manifold 15 extends downwardly to an en-` trance opening 18 adjacent thebottom of cach section leading to a conduit or passage 19 extendineracross the bottom thereof and opening int-o the outlet manifold 12through an outlet opening 20 at its opposite end. A partition plate 21separates the bottom of the counter fiow passage 9 from the cross flowpassage or conduit 19.

In the particular form of the invention illustrated in Fig. 5 the inlet18 .is spaced from the bottom of the section and leads to a conduit orpassage 22 through which the second stream of air flows from themanifold 15 to the outlet 20 in a circuitous route counter to the flowof the heating` gases formed by baffles 23. The result is that, insteadof the second stream of air'flowing in a straight direction across thebottom of the section, there is formed, in effect, a second counterlcurrent flowing stream which takes the utmost advantage of the intenseheat at that portion of the apparatus. In this form, the partition 21 1sextended into the manifold 15 and bent downwardly to form a baille 24which directs the cold stream of air flowing through the manifolddownwardly and across the bottomsurface thereof and thence upwardly tothe rnlet 18 so as to prevent the formation of an a1r pocket in thebottom of the manifold 1 5 which would result in burningout the materlalof the apparatus at that point.

Each 'lnlet is provided with a valve 25 of an deslred form for thepurpose of indiv1 ually controlling the ilow of air in the two streams.p f

An automatically operated control isV provided for the purpose ofmaintaining a predetermined flow through and across the bottom of theapparatus, regardless of the total amountof air which may be flowingthrough the entire device, and this mechanism will operate so as toprevent any flow through the counter current passage 9 until the flowthrough the cross current passage 19 or 22 has acquired a predeterminedcharacteristic such, for example, as ay predetermined velocity or a.predetermined quantity flow 0r the like.

As illustrated, this automatic mechanism comprises a damper 26 securedto a rod 27 rotatably mounted in the sides of the supply hne 7 at theend of the inlet 6 to the counter current passage. The damper or valve26 is 14 to the cross counter passage 19 or 22 will not operate to openthe damper 26 so as to cause a flow through the counter passage 9 untilthe flow through the cross current passage has .become a predeterminedquantity or has acquired some other predetermined characteristic. Itwill be apparent that above a certain flow the quantity flow orvelocity. as the case may be, of the air stream through the crosscurrentpassage will be maintained substantially constant, regardless ofvariation; in the total quantity of flow through the entire apparatus.Such variations intotal flow as normally result from the usual operationof this form of device will aect only the stream fiowing through thecounter current p assage while the flow of the streamr of relativelycold air which is fed through the hotvtest part of the apparatus,namely, across the bottom thereof, will -be maintained relatlvelyconstant and such fiow can be accurately predetermined so as to obtainthe most efficient rate of heat exchange at this point.

Although I have described a specific adaptation of this invention itwill be apparent that various changes, additions, omissions orsubstitutions can be made therein 5 without departing' from the spiritof the invention or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is: i

1. The combination in a heat exchange apparatus of a passage adapted todirect a flow of fluid counter-current to the flow of heating gases, apassage for a relatively cold stream across the end of said apparatussubjected to the highest temperature, an outlet manifold communicatingwith both of said passages and separate manifolds for -said passages.

2. A heat exchange apparatus having in combination an inlet, a passagefor directing a stream of fluid from -said inlet through said apparatusin a direction counter to the direction ofl flow of heating gases withwhich the apparatus is associated, a second inlet, a second passage fordirecting a stream of fluid from said second inlet across that part oftheapparatus subjected tothe highest temperature, a common outlet forsa1d' streams and' means for maintaining the flow through said secondpassage at a predetermined velocity.

3. The combination in a heat exchange apparatus of a passage adapted todirect a flow therethrough in a counter current di- 4 rection withrelation of the. flow of heating r gases, a passage for a relativelycold stream across the end of said apparatus subjected to the highesttemperature, an outlet manifold communicating with both of saidpassages, separate inlets for said passages and means for individuallycontrolling the flow through each inlet.

4. Av heat exchange apparatus having'in combination an inlet, a passageassociated with said inlet for directing a stream of fluid through theapparatus, a second inlet, a second passage associated therewith fordirect-` ing a stream of uid across that part of the apparatus subjectedto the highest temperature and a valve associatedwith said first r inletand adaptedto be operated by the pressure therein formaintaining theflow through said second inlet substantially constant.

5. A heat exchange apparatus having in combination an inlet, a passageassociated with said inlet for directing a stream of fluid through theapparatus, 'a second inlet, a second passage associated therewith fordirecting a stream of fluid across that'part of the apparatus subjec-tedt0 the highest tempera-V ture and an eccentrically supported damperassociated with said first in to be operated by the pressure therein formaintaining the flow through said second inlet substantially constant.

6. A heat exchange apparatus having in et and adapted combination aninlet, a passage associated with said inlet for directing a stream offluid through the apparatus, a second inlet, a second passage associatedtherewith for directing a stream of fluid across that part of theapparatus subjected to the highest temperature and a counter weighteddamper associated with said first inlet and adapted to be operated bythe pressure therein for main-v taining the flow through said Isecondinlet substantially constant.

7 The combination in a heat exchange apparatus of separate passage forthe transmission of fluid to be heated therethrough, means forcontrolling the transmission of fluid through each of said passages,means for normally preventing the flow of fluid the other of saidpassages has acquired a predetermined velocity.

9. The combination in a` heat exchange apparatus having separatepassages for the transmission of fluid therethrough and valvescontrolling the separate passages, of means for controlling theadmission of fluid to 'one of said passages and mechanism forcontrolling the operation of said means so that variationsin the totalflow through the apparatus cause yvariations in the velocityof flowthrough one of said passages only.

10. The combination in a heat exchange apparatus having separatepassages for the transmission of 'fluid therethrough and valvescontrolling the separate passages, of al flow control damper adapted tonormally close one of said passages and means renderlngxsaid damperoperable to permit flow through the associated passage when the flowthrough the other of said passages reaches a .predetermined velocity. y

11. The combinationin a heat exchange counter-current to the directionofflow of the heating gases, a passage for a flow of fluid through theapparatus adjacent an associated combustion chamber and a damperoperated by the flow of fluid for preventing any flow through saidcounter-current pas- A sage until the flow through said other passagehas acquired a predetermined velocity.

In testimony whereof, I have hereunto subscribed my name this 2nd day ofApril, 1926.

GREGORY D. MANTLE.

apparatus of a passage for the flow of fluid

